Stand Alone Rainwater Harvesting System
The Two Dollar Tank- a new method for Rainwater Harvesting in Developing Countries
by RainSaucers Inc. on February 19th, 2014

It's something that's been bothering me for a long time. We have this great product that could help a lot people in developing countries. But each time we get close to some sort of arrangement with a local partner, the topic of water storage comes up. That's where the discussion ends because of total cost- the poor simply cannot afford the tank our system needs. So I'd been wondering how to make a RainSaucer™ that comes with its own tank- for dirt cheap no less. Then it hit me- on KickStarter we see cardboard bikes, cardboard furniture, cardboard speakers. Why not a cardboard tank and RainSaucer™?  It could work as long as we could find a method for waterproofing the cardboard. So  I put the challenge to my new industrial design interns Claudine Zafra and Ray Chen from San Jose State and after significant trial and error we have a few prototypes that are now working. 

Today we issued a press release about our new project- "The Two Dollar Tank" (pictured above, more pictures below).  As the name suggests, the Two Dollar Tank is a rainwater collection system that can be manufactured for less than two dollars making it an ideal solution for the developing world. The key to the low cost is the use of heavy duty carboard for the frame lined by 2 Mil polyethylene sheet inside and out. The idea is similar to that of a water bag but with the cardboard structure to relieve pressure on the bag and allow for access from the top . The open top also allows us to add a RainSaucer™ for standalone collection or as a gutter substitute.  Specs of the system:
  • Tank dimensions are 18" x 18" x 24"
  • Tank holds 4.5 Cubic Feet of Storage or 33.6 Gallons/144 liters
  • 40" octogonal RainSaucer collects rain stand alone or off a roof.
  • In standalone mode, collection surface of approx. 8 square feet= 5 gallons/inch of rain.
  • In roof collection mode surface can increase to 30 square feet= 18 gallons/inch of rain.
  • System is Foldable down to approx. 18" x 24" x 4"
  • Total weight including siphon pump is under 2lbs
  • 100% DIY. User installs tank by folding out bottom flaps on flat suface. RainSaucer rests on top and is secured by string around entire system.
  • Water is removed by lifting up RainSaucer and scooping out water or by low cost Siphon Pump (which can be purchased wholesale from China and customized for well under $1)
  • Expected life of system is 1-3 years. 
The Two Dollar Tank project is currently in the final stages of product development, What we need now is an NGO interested in teaming up with us to finalize the design and field test it. Please contact us if you are interested. 

​More photos and the Bill of Materials are available below.


We start with an 18" x 18" x 24" Box and line it inside and out with 2Mil Black PE Sheet
The RainSaucer is also lined with PE Sheet. It goes on top and is tied down with string.
Top View.
The removable strainer in the Center keep outs debris, bugs, and critters.
When filled with water the tank expands but contracts back when empty.
The added plastic at the bottom of the RainSaucer keeps it in place even when the tank expands from water.
Water can be dispensed with  a Siphon Pump that has been extended. Siphon Action will allow for automatic drainage once flow is established.
The compact form means the system can be easily transported or shipped in case of use for Disasters.
The final retail price could for the initial system would be near $5 - easily affordable by the Bottom of the Pyramid.  Replacement tanks would be available for $2.50.
The Two Dollar Tank Team- from left to right: Tom Spargo, Ray Chen, and Claudine Zafra


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